1. Field of the Invention
The present invention relates to a base station apparatus used in mobile communication.
2. Description of the Background Art
Generally, for efficient use of radio waves, a cellular system is employed in mobile communication such as in a portable phone system or PHS (Personal Handyphone System). That is, a large number of base stations adapted to a number of cells are required.
In addition, in recent days, a diversity reception system or adaptive array processing is employed. In such a diversity reception system or adaptive array processing, a plurality of antennas are used in each base station, which are installed according to a prescribed arrangement, for example, on a circumference. With the diversity reception system or adaptive array processing, improvement of gain, elimination of interference, or improvement in efficiency in utilizing radio waves is achieved.
In an antenna installation work at a base station requiring such a plurality of antennas, cables from the plurality of antennas should be connected to a main body of a base station apparatus. The number of antenna cables that should be connected to the main body of the base station apparatus corresponds to the number of the antenna elements, and further, the base station apparatus is located distant from the antennas. Accordingly, the connection work tends to be difficult to some extent.
FIG. 11 illustrates the work for connection between the antennas and the base station apparatus main body.
Referring to FIG. 11, antennas ANT1 to ANT8 arranged on a circumference are provided at an upper end of a post P. A box B is provided at a lower portion of post P, in which a base station apparatus is housed. Antennas ANT1 to ANT8 are connected to the base station apparatus via cables CB1 to CB8 respectively.
FIG. 12 is a block diagram showing a configuration of a conventional base station apparatus 501.
Referring to FIG. 12, base station apparatus 501 includes a first radio transmission/reception circuit 503 performing transmission/reception using antennas ANT1, ANT3, ANT5, ANT7 and a second radio transmission/reception circuit 506 performing transmission/reception using antennas ANT2, ANT4, ANT6, ANT8.
Base station apparatus 501 further includes a first digital signal processing circuit 504 provided corresponding to radio transmission/reception circuit 503, a second digital signal processing circuit 504 provided corresponding to radio transmission/reception circuit 506, a channel interface circuit 505 serving as an interface between digital signal processing circuits 504, 507 and communication network, and a control circuit 508 serving for overall control over each circuit in base station apparatus 501.
As shown in FIG. 12, in recent years, the base stations equipped with a plurality of radio transmission/reception circuits (tuners) are often used so that more users can establish communication in an area covered by one base station. The plurality of radio transmission/reception circuits use frequency channels different from each other in an identical frequency band.
The plurality of radio transmission/reception circuits may share an antenna. In such a case, however, a circuit which combines radio waves emitted from a plurality of radio transmission/reception units for transmission to an antenna is required in the base station apparatus. Accordingly, the base station apparatus main body will become expensive.
For example, in accordance with frequency of use by users, a base station equipped with a plurality of radio transmission/reception circuits may be adopted in an urban area, while a base station equipped with a single radio transmission/reception circuit may be adopted in a suburban or mountain area. In such a case, it is more convenient to provide antennas separately for each radio transmission/reception circuit, because a component for the radio transmission/reception circuit can be shared.
FIG. 13 illustrates an example of connection between the antennas shown in FIG. 11 and the base station apparatus shown in FIG. 12.
Referring to FIG. 13, in diversity reception for example, reception is preferably achieved using two antennas located distant from each other, instead of using two antennas proximate to each other. From such a point of view, for example, antennas are preferably arranged in a group G1 and a group G2 corresponding to two tuners respectively.
For example, if antennas ANT1 and ANT2 are allocated to one tuner, the antennas are arranged proximate to each other in terms of space. Therefore, if communication is affected by a neighboring building or the like, reception status at both antennas ANT1 and ANT2 predictably becomes poor. When reception at antenna ANT1 is poor, reception at antenna ANT5 should be enabled. In other words, in allocating antennas to one tuner, antennas are preferably arranged in a distributed manner, instead of allocating antennas proximate to each other like a cluster.
It is noted that Japanese Patent Laying-Open No. 10-41873 provides description on an installation work of a base station apparatus.
On the other hand, in a conventional base station shown in FIGS. 11 and 12, a plurality of cables should be connected to connectors of the base station in a preferred connection relation as shown in FIG. 13 during an antenna installation work. In doing so, labels indicating such a preferred connection relation with antennas should be provided at end portions of cables on the side to be connected to the connectors of the base station. Even with such labels, misconnection may take place during the work. In such a case, maximum performance of the base station apparatus cannot be exhibited.